|標題：||理論インフォーマルセミナー：On the number of Nambu-Goldstone bosons and its relation to charge densities|
|講師：||渡辺 悠樹 氏|
|所属：||University of Tokyo and UC Berkeley|
|要旨：||The importance of Spontaneous Symmetry Breaking (SSB) and the associated
Nambu-Goldstone (NG) bosons is widely understood not only in particle physics but also in other fields, including condensed matter physics. Although the physics of NG bosons is well-understood in relativistic systems, once we discard the Lorentz symmetry the precise characterization of the number and dispersion relations is still an open problem.
I will give an overview of our recently proposed conjecture which relates the number of NG bosons with the generalized charge density of the ground state . In addition, I will briefly explain a framework to handle SSB of transnational invariance itself. As an example, (ferromagnetic) supersolid will be discussed .
 H. Watanabe, T. Brauner, Phys. Rev. D 84, 125013 (2011), arXiv:1109.6327
 H. Watanabe, T. Brauner, to be submitted to PRA, arXiv: 1112.3890
|世話人：||押川 正毅 (内線：63275)
e-mail: oshikawa :at: issp.u-tokyo.ac.jp